CN107452969B

CN107452969B - Bus bar

Info

Publication number: CN107452969B
Application number: CN201710385332.XA
Authority: CN
Inventors: 关根广之
Original assignee: Toyota Motor Corp
Current assignee: Toyota Motor Corp
Priority date: 2016-05-31
Filing date: 2017-05-26
Publication date: 2020-05-12
Anticipated expiration: 2037-05-26
Also published as: US9979165B2; DE102017109337A1; DE102017109337B4; CN107452969A; JP2017216092A; JP6579039B2; US20170346262A1

Abstract

A bus bar is provided, which can restrain the size of the bus bar used in a fuel cell system from increasing. A bus bar used in a fuel cell system including a fuel cell, an FC boost converter as a DC-DC converter for boosting a voltage output from the fuel cell, and an inverter connected to the FC boost converter, includes: a first bus bar connected to a negative terminal of the fuel cell; a second bus bar connected to a negative terminal of the FC boost converter; and a third bus bar connected to a negative terminal of the inverter. The second bus bar is directly connected to the first bus bar, and the third bus bar is directly connected to the first bus bar. The cross-sectional area of the second bus bar is smaller than the cross-sectional area of the first bus bar.

Description

Bus bar

Technical Field

The present invention relates to a bus bar used in a fuel cell system.

Background

Patent document 1 discloses a fuel cell system provided with a fuel cell, an FC boost converter (hereinafter, also simply referred to as "boost converter") for boosting a voltage output from the fuel cell, and an inverter for supplying the boosted voltage output from the boost converter, as a fuel cell system mounted on a vehicle.

Documents of the prior art

Patent document

Japanese patent laid-open publication No. 2015-and 220961 of patent document 1

Disclosure of Invention

Problems to be solved by the invention

In the above fuel cell system, the electrical connection between the negative terminal of the fuel cell and the negative terminal of the boost converter is performed using a bus bar. Further, the electrical connection between the negative terminal of the boost converter and the negative terminal of the inverter is also performed using a bus bar. The allowable current of the bus bar is proportional to its sectional area. For example, in the case where the thickness of the bus bar is constant, the larger the allowable current of the bus bar is, the larger the width of the bus bar is. Conventionally, as a bus bar connecting the negative terminal of the fuel cell and the negative terminal of the boost converter, a bus bar having a current capacity that allows a current that is the sum of a current flowing through the negative terminal of the boost converter and a current flowing through the negative terminal of the inverter is generally used. Therefore, the bus bar between the negative electrode terminal of the fuel cell and the negative electrode terminal of the boost converter has a problem that the sectional area becomes large and the size becomes large. Further, when the bus bar is large in size, there is a problem that various components and members included in the fuel cell and the boost converter are likely to interfere with the bus bar, and therefore, in order to prevent this, the arrangement interval of the components and members has to be increased, and a space required for arrangement of the fuel cell system is increased.

Means for solving the problems

The present invention has been made to solve at least part of the above problems, and can be realized as the following embodiments.

(1) According to an aspect of the present invention, there is provided a bus bar used in a fuel cell system. The fuel cell system includes: a fuel cell; an FC step-up converter that is a DC-DC converter that steps up a voltage output from the fuel cell; and an inverter connected to the FC boost converter. The bus bar is provided with: a first bus bar connected to a negative terminal of the fuel cell; a second bus bar connected to a negative terminal of the FC boost converter; and a third bus bar connected to a negative terminal of the inverter. The second bus bar is directly connected to the first bus bar, the third bus bar is directly connected to the first bus bar, and a sectional area of the second bus bar is smaller than a sectional area of the first bus bar.

The current flowing through the second bus bar is supplied from the fuel cell to the FC step-up converter, and becomes a difference between the current flowing from the negative terminal of the FC step-up converter through the second bus bar and the first bus bar and returning to the negative terminal of the fuel cell and the current supplied from the FC step-up converter to the inverter and flowing from the negative terminal of the inverter through the third bus bar and the second bus bar and returning to the negative terminal of the FC step-up converter, that is, a difference between the current flowing through the first bus bar and the current flowing through the third bus bar. Therefore, the sectional area of the second bus bar connected to the FC step-up converter can be made smaller than the sectional area of the first bus bar connected to the fuel cell, and therefore the bus bar can be reduced in size. This can prevent the bus bar from interfering with various components or members included in the fuel cell and the FC step-up converter, and the arrangement interval of the components or members from increasing, which can increase the space required for arranging the fuel cell system.

(2) In the bus bar of the above aspect, a sectional area of the third bus bar may be smaller than the sectional area of the first bus bar.

According to this aspect, the bus bar can be further reduced in size.

(3) In the bus bar of the above aspect, the first bus bar may be integrally formed with the second bus bar.

According to this aspect, since the first bus bar and the second bus bar are integrally formed, the connection resistance between the first bus bar and the second bus bar can be reduced as compared with a case where different first bus bar and second bus bar are coupled via a fastening means such as a bolt.

The present invention can be implemented in various forms, such as a bus bar used in a fuel cell system, and the like.

Drawings

Fig. 1 is an explanatory view showing a schematic configuration of a fuel cell system as an embodiment.

Fig. 2 is an explanatory diagram showing a schematic configuration of a fuel cell system of a comparative example.

Fig. 3 is an explanatory diagram showing currents flowing through the first to third bus bars in the fuel cell system of the comparative example.

Fig. 4 is an explanatory diagram showing currents flowing through the first to third bus bars in the fuel cell system of the embodiment.

Fig. 5 is an explanatory view showing an example of the mounting arrangement of the first to third bus bars.

[ description of reference ]

10 … fuel cell

20 … boost converter for fuel cell (FCDC)

22 … reactor unit (LU)

24 … semiconductor element Module for Power (IPM)

30 … Inverter (INV)

40 … driving motor

Cs … smoothing capacitor

SD … switchgear

LC … cable

Lr … reactor

K1 and K2 … connector

KP1 … positive terminal

KN1 … negative terminal

KP2 … positive terminal

KN2 … negative terminal

Positive terminal of P1 … fuel cell

Negative terminal of N1 … fuel cell

P2i … positive terminal on input side

Positive terminal of P2o … output side

Negative terminal of N2 … boost converter

Positive terminal of P3 … inverter

Negative terminal of N3 … inverter

B1-B3 … bus bar

End of B2e … Secondary bus Bar

TB 1-TB 3 … connection point

C12 … connecting part

Negative terminal of Tfc … fuel cell

WB 1-WB 3 … width

HB 1-HB 3 … thickness

IB1-IB3 … bus bar current

Ifc … Battery output Current

Ih … converter output current

Detailed Description

A. The implementation mode is as follows:

fig. 1 is an explanatory view showing a schematic configuration of a fuel cell system as an embodiment. This fuel cell system is shown by way of example as a fuel cell system mounted on a fuel cell vehicle. However, the present invention is not limited to this, and a stationary fuel cell system may be used.

The fuel cell system includes a fuel cell (referred to as "FC" in the figure) 10, an FC boost converter (referred to as "FCDC" in the figure) 20, an inverter (referred to as "INV" in the figure) 30, and a drive motor 40.

The fuel cell 10 is a power generation device having a stack structure in which a plurality of unit cells each including a membrane electrode assembly (not shown) as a power generation body that generates electric power by an electrochemical reaction between a fuel gas and an oxidizing gas are stacked in series. Various devices for causing the fuel cell 10 to function as a power generation device, such as a fuel gas supply device, an oxidizing gas supply device, and a cooling device, are provided as the fuel cell system, but are not particularly relevant to the present invention, and therefore, illustration and description thereof are omitted.

The FC step-up converter 20 is, for example, a multiphase step-up DC-DC converter having a plurality of drive phases (for example, 4 phases) and a smoothing capacitor Cs, and is a circuit that steps up a voltage output from the fuel cell 10. But may be a single phase boost DC-DC converter of 1 drive phase. The 1 drive phase is constituted by a boost chopper circuit having a reactor Lr and a switching device SD. As the reactor Lr of each drive phase, a plurality of reactors included in 1 reactor unit (referred to as "LU" in the drawing) 22 are used. As the switching devices SD and the smoothing capacitors Cs of the respective drive phases, a plurality of switching devices and smoothing capacitors included in the Power semiconductor device module 24 called ipm (intelligent Power module) are used. Hereinafter, the power semiconductor element module 24 is referred to as "IPM 24".

The inverter (referred to as "INV" in the drawing) 30 is a drive circuit that converts dc power supplied from the FC step-up converter 20 into ac power and supplies the ac power to the drive motor 40. The drive motor 40 receives ac power from the inverter 30 and drives wheels, not shown. The inverter 30 supplies ac power of the number of phases corresponding to the type of motor used for the drive motor 40 to the drive motor 40. For example, when the drive motor 40 is a synchronous motor having three-phase coils, the inverter 30 supplies three-phase ac power to the drive motor 40.

The positive electrode terminal P1 of the fuel cell 10 is electrically connected to the input-side positive electrode terminal P2i of the FC step-up converter 20. The reactors Lr of the reactor unit 22 are electrically connected in parallel to the positive electrode terminal P2 i. The output-side positive terminal P2o of the FC boost converter 20 is electrically connected to the positive terminal P3 of the inverter 30 via the positive terminal KP1 of the first connector K1, the cable LC, and the positive terminal KP2 of the second connector K2.

The negative electrode terminal N1 of the fuel cell 10, the negative electrode terminal N2 of the FC step-up converter 20, and the negative electrode terminal N3 of the inverter 30 are electrically connected as described below. That is, the negative electrode terminal N1 of the fuel cell 10 is electrically connected to the first bus bar B1 at the connection point TB1 at one end of the first bus bar B1. The negative terminal N2 of the FC voltage boost converter 20 is electrically connected to the second bus bar B2 at a connection point TB2 at one end of the second bus bar B2. The negative terminal N3 of the inverter 30 is electrically connected to one end of the third bus bar B3 via the negative terminal KN2 of the second connector K2, the cable LC, and the negative terminal KN1 of the first connector K1.

An end of the second bus bar B2 opposite to the end having the connection point TB2 and an end of the first bus bar B1 opposite to the end having the connection point TB1 are directly connected by a connection portion C12, thereby electrically connecting the first bus bar B1 and the second bus bar B2. The third bus bar B3 is directly coupled to the first bus bar B1 at a connection point TB3 in the vicinity of the first bus bar B1 side of the coupling portion C12 of the first bus bar B1 and the second bus bar B2 to be electrically connected. Thereby, the negative electrode terminal N1 of the fuel cell 10, the negative electrode terminal N2 of the FC step-up converter 20, and the negative electrode terminal N3 of the inverter 30 are electrically connected. The coupling of the primary bus bar B1 and the secondary bus bar B2 is performed by integrally forming the primary bus bar B1 and the secondary bus bar B2. The coupling of the first bus bar B1 and the third bus bar B3 is performed by fastening members (not shown) via bolts or the like at the connection point TB 3.

The cross sections of the 3 bus bars B1, B2, B3 are rectangular shapes, respectively. Hereinafter, among the dimensions of the lengths of the sides of the cross sections of the bus bars B1, B2, and B3, the smaller dimension is referred to as "thickness", and the larger dimension is referred to as "width". In fig. 1, the size in the direction perpendicular to the paper surface in the drawing corresponds to "thickness", and the size in the direction parallel to the paper surface in the drawing corresponds to "width".

In the present embodiment, the thickness HB1 of the first bus bar B1, the thickness HB2 of the second bus bar B2, and the thickness HB3 of the third bus bar B3 are set to be the same, and the width WB2 of the second bus bar B2 and the width WB3 of the third bus bar B3 are smaller than the width WB1 of the first bus bar B1, respectively. That is, the second bus bar B2 has a cross-sectional area (WB2 HB2) smaller than the cross-sectional area (WB1 HB1) of the first bus bar B1. The third bus bar B3 also has a cross-sectional area (WB3 HB3) smaller than the cross-sectional area (WB1 HB1) of the first bus bar B1.

Fig. 2 is an explanatory diagram showing a schematic configuration of a fuel cell system of a comparative example. The electrical connection between the negative terminal N1 of the fuel cell 10, the negative terminal N2 of the FC step-up converter 20, and the negative terminal N3 of the inverter 30 of the fuel cell system of the comparative example is different from the embodiment as described below. In the embodiment, as shown in fig. 1, the third bus bar B3 is electrically connected to the first bus bar B1 in series at a connection point TB3 connected to the first bus bar B1 in the vicinity of the connection portion C12 of the first bus bar B1 and the second bus bar B2. In contrast, in the comparative example, as shown in fig. 2, the third bus bar B3 is directly connected to the second bus bar B2 and electrically connected thereto at a connection point TB3 connected to the end B2e of the second bus bar B2 located on the opposite side of the connection portion C12 between the first bus bar B1 and the second bus bar B2 with respect to the connection point TB2 connected to the negative terminal N2 of the FC voltage boost converter 20. The width WB2 and the thickness HB2 of the second bus bar B2 connected to the negative terminal N2 of the FC boost converter 20 are equal to the width WB1 and the thickness HB1 of the first bus bar B1 connected to the negative terminal N1 of the fuel cell 10, and the first bus bar B1 and the second bus bar B2 are integrally formed. That is, the difference is that the width WB2 of the second bus bar B2 of the comparative example is the same as the width WB1 of the first bus bar B1, whereas the width WB2 of the second bus bar B2 of the embodiment is smaller than the width WB1 of the first bus bar B1.

Fig. 3 is an explanatory diagram showing currents flowing in bus bars in the fuel cell system of the comparative example. Fig. 4 is an explanatory diagram showing currents flowing in the bus bars in the fuel cell system of the embodiment. In fig. 3 and 4, for convenience of explanation, the connectors K1 and K2 and the cable LC between the third bus bar B3 and the inverter 30 are omitted, and the bus bars are indicated by solid lines. The case where there is no loss in each circuit will be described.

As shown in fig. 3, in the case of the comparative example, the battery output current Ifc supplied from the positive electrode terminal P1 of the fuel cell 10 to the FC voltage boost converter 20 flows from the connection point TB2 to the second bus bar B2 and the first bus bar B1 via the positive electrode terminal P2i and the negative electrode terminal N2 on the input side of the FC voltage boost converter 20, and returns from the connection point TB1 to the negative electrode terminal N1 of the fuel cell 10. The converter output current Ih supplied from the positive terminal P2o on the output side of the FC voltage boost converter 20 to the inverter 30 flows to the third bus bar B3 via the positive terminal P3 and the negative terminal N3 of the inverter 30, flows from the connection point TB3 connected to the second bus bar B2 to the end B2e of the second bus bar B2, and returns from the connection point TB2 to the negative terminal N2 of the FC voltage boost converter 20. Therefore, the second bus bar current IB2 flowing from the second bus bar B2 toward the first bus bar B1 and the first bus bar current IB1 flowing in the first bus bar B1 become the battery output current Ifc. Therefore, in the case of the comparative example, in order to make the sectional area (WB2 · HB2) of the second bus bar B2 equal to the sectional area (WB1 · HB1) of the first bus bar B1, the width WB2 and the thickness HB2 of the second bus bar B2 are required to be equal to the width WB1 and the thickness HB1 of the first bus bar B1.

In contrast, in the case of the embodiment, as shown in fig. 4, the converter output current Ih supplied from the positive terminal P2o on the output side of the FC boost converter 20 to the inverter 30 flows to the third bus bar B3 via the positive terminal P3 and the negative terminal N3 of the inverter 30. The converter output current Ih flowing through the third bus bar B3 flows from the connection point TB3 connected to the first bus bar B1 toward the second bus bar B2 in reverse to the battery output current Ifc, and returns from the connection point TB2 to the negative terminal N2 of the FC voltage boost converter 20. Therefore, the second bus bar current IB2 flowing in the second bus bar B2 becomes a difference (Ifc-Ih) between the battery output current Ifc and the converter output current Ih, that is, a difference (IB1-IB3) between the first bus bar current IB1 and the third bus bar current IB 3. Thus, the sectional area (WB2 · HB2) of the second bus bar B2 can be made smaller than the sectional area (WB1 · HB1) of the first bus bar B1. In this example, as shown in fig. 1, the thickness HB2 is the same as the thickness HB1 of the first bus bar B1, and the width WB2 is smaller than the width WB1 of the first bus bar B1, so that the cross-sectional area (WB2 · HB2) of the second bus bar B2 is smaller than the cross-sectional area (WB1 · HB1) of the first bus bar B1. In the comparative example of fig. 3 (fig. 2), since the first bus bar B1 and the second bus bar B2 are substantially constituted by 1 bus bar, it is apparent from a comparison of the drawings that the number of bus bars in the embodiment of fig. 4 (fig. 1) is increased. As is clear from comparison of the drawings, the third bus bar B3 of the embodiment is longer than the third bus bar B3 of the comparative example. However, this is merely for ease of illustration. In fact, in the comparative example, the cross-sectional area of the portion of the second bus bar B2 can be reduced to the state of the embodiment by merely changing the positions of the connection points TB2 and TB3, and there is no substantial difference in the number of bus bars and the length of the third bus bar B3.

In addition, the third bus bar current IB3 flowing in the third bus bar B3 is the converter output current Ih, that is, the difference between the first bus bar current IB1 and the second bus bar current IB2 (IB1-IB 2). Therefore, the sectional area (WB3 · HB3) of the third bus bar B3 can be smaller than the sectional area (WB1 · HB1) of the first bus bar B1, as with the second bus bar B2. In this example, as shown in fig. 1, the thickness HB3 is the same as the thickness HB1 of the first bus bar B1, and the width WB3 is smaller than the width WB1 of the first bus bar B1, so that the cross-sectional area (WB3 · HB3) of the third bus bar B3 is smaller than the cross-sectional area (WB1 · HB1) of the first bus bar B1.

Fig. 5 is an explanatory view showing an example of the mounting arrangement of the bus bar. As shown in fig. 5, in the space of the gap between the reactor unit 22 and the IPM24 constituting the FC step-up converter 20, a connection point TB1 between the connection point C12 of the first bus bar B1 and the second bus bar B2, the connection point Tfc of the terminal Tfc corresponding to the negative electrode terminal N1 of the fuel cell 10 and the first bus bar B1, and a connection point TB3 between the first bus bar B1 and the third bus bar B3 are arranged. The second bus bar B2 is bent along the space of the gap, and is electrically connected to the IPM24 of the FC boost converter 20 at the connection point TB 2.

As shown in fig. 5, the bus bar of the embodiment can reduce the size of the whole bus bar by reducing the size of the second bus bar B2. Further, since the degree of freedom in the arrangement of the second bus bars can be increased by reducing the size of the second bus bar B2, it is possible to suppress the increase in the arrangement size between the components, which has been conventionally performed, in order to avoid interference between the bus bars and the components or members arranged in the periphery. Further, since the size of the third bus bar B3 can be reduced, the overall size of the bus bar can be further reduced. Further, since the degree of freedom of the arrangement of the third bus bar B3 can be increased by reducing the size of the third bus bar B3, it is possible to suppress the increase in the arrangement size between the components, which has been conventionally performed, in order to avoid interference between the bus bar and the components and members arranged in the periphery.

B. Modification example:

(1) in the above embodiment, the case where the thicknesses HB1 to HB3 of the 3 bus bars B1 to B3 are the same, the width WB2 of the second bus bar B2 is smaller than the width WB1 of the first bus bar B1, and the width WB3 of the third bus bar B3 is smaller than the width WB1 of the first bus bar B1 has been described as an example, but the present invention is not limited thereto. The widths WB1 to WB3 may be the same, the thickness HB2 of the second bus bar B2 may be smaller than the thickness HB1 of the first bus bar B1, and the thickness HB3 of the third bus bar B3 may be smaller than the thickness HB1 of the first bus bar B1. Further, both the width WB2 and the thickness HB2 of the second bus bar B2 may be made smaller than the width WB1 and the thickness HB1 of the first bus bar B1, and both the width WB3 and the thickness HB3 of the third bus bar B3 may be made smaller than the width WB1 and the thickness HB1 of the first bus bar B1. In short, the sectional area (WB2 · HB2) of the second bus bar B2 may be smaller than the sectional area (WB1 · HB1) of the first bus bar B1, and the sectional area (WB3 · HB3) of the third bus bar B3 may be smaller than the sectional area (WB1 · HB1) of the first bus bar B1. However, from the point that 3 bus bars B1 to B3 can be easily formed from one plate material, a structure in which the thickness is the same and the width is changed is preferable.

(2) In the above embodiment, the case where the first bus bar B1 and the second bus bar B2 are formed as an integral bus bar was described as an example, but the bus bars may be formed as separate bus bars, and the ends may be connected and electrically connected by fastening members such as bolts.

(3) In the above embodiment, the case where the third bus bar B3 is a bus bar different from the first bus bar B1 independently has been described as an example, but may be integrated with the first bus bar in the same manner as the second bus bar B2. That is, all of the 3 bus bars B1 to B3 may be integrally formed. In this way, the connection resistance between the first bus bar B1 and the third bus bar B3 can be reduced.

The present invention is not limited to the above-described embodiments, examples, and modifications, and can be implemented in various configurations without departing from the spirit thereof. For example, the technical features of the embodiments, examples, and modifications corresponding to the technical features of the respective aspects described in the section of the summary of the invention may be replaced or combined as appropriate in order to solve a part or all of the above-described problems or to achieve a part or all of the above-described effects. In addition, the technical features may be deleted as appropriate as long as they are not described as essential features in the present specification.

Claims

1. A bus bar for use in a fuel cell system, wherein,

the fuel cell system includes:

a fuel cell;

an FC step-up converter that is a DC-DC converter that steps up a voltage output from the fuel cell;

an inverter connected to the FC boost converter; and

the bus bar is provided with a plurality of bus bars,

the bus bar is provided with:

a first bus bar connected to a negative terminal of the fuel cell;

a second bus bar connected to a negative terminal of the FC boost converter; and

a third bus bar connected to a negative terminal of the inverter,

the second bus bar is directly coupled to the first bus bar,

the third bus bar is directly coupled to the first bus bar,

the cross-sectional area of the second bus bar is smaller than the cross-sectional area of the first bus bar.

2. The bus bar according to claim 1,

a cross-sectional area of the third bus bar is smaller than the cross-sectional area of the first bus bar.

3. The bus bar according to claim 1 or 2,

the first bus bar is formed integrally with the second bus bar.